Insulating tube and process of making same



H. H. WERMINE INSULATING TUBE AND PROCESS OF MAKING SAME Filed A ril 15.19

a OWTY J fir Hugo H Wrrm ay/ W! 54 W "Patented Dec. 4, 1928.

AT'ENT @FHQE.

HUGO H. WERMINE, OF CHICAGO, ILLINOIS,

ING COMPANY, OF CHICAGO, ILLINOIS,

ASSIG-NOR TO BELDEN MANUFACTUR- A CORPORATION 016 ILLINOIS.

l INSULATING TUBE AND- PROCESS OF MAKING- SAME.

Application filed April 15, 1922. Serial No. 553,286.

wires.

The principal object of the invention is to provide an improvedinsulating tube or sheathing which may be manufactured at relatively lowcost, which shall have high dielectric strength, which shallbe-form-sustaining, substantially waterproof and through which bare orother wires may readily be inserted.

In the drawings accompanying this application:

Fig. 1 is a diagrammatic elevation of apparatus which may be employedfor manufacturing my imp, roved tube;

Fig. 2 is a section taken on the line 22 of Fig. 1; and

Fig. 3 is a section of Fig. 1.

Heretofore it has been the practice, in general, to use two differentforms of insulating tubes for removably containing wires leading to theterminals of the electric coils or analogous apparatus. Braided sleev nghas taken on the line 3- 3 been used to a considerable extent, but suchsleeving has the disadvantage that it is not.

form-sustaining, and, also, although attempts have been made to treatsame with varnish, the dielectric strength of the sleeving has beenrelatively low.

i There also has been used what in the trade is known as Itala tubing,this consisting of a continuous tube of linen impregnated or otherwisetreated with a material of high dielectric strength. However, this Italaor Empire? tubing up to the present tlme has usually been imported atgreat cost, and its use on that account hasbeen confined to relativelyexpensive apparatus.

In producing tubing according to my in vention, any desired form ofapparatus may be employed, but I prefer to use apparatus similar to thatshown in the drawings. In such drawings I have illustrateddiagrammatically two spools 10 of any desired type of braiding machine,it being understood that the machine is equipped wlth eight, twelve,sixteen or any other customary number of spools, the paths of whichspools in traveling around the center of the machine cross each ojtfher,thus forming the interwoven braid e ect.

At the center of the machine and just beif the varnish is of the air lowwhere the laying on of the braiding threads 11 occurs, in place of theordinary guide I equip the machine with a die 12 having a tapering bore13, the lower end of the bore being considerably greater in diameterthan the upper end of the bore. Below the bottom of the die 12 Ipreferably use a preforming die 14;, said die being cut in two parts, asshown in Fig. 2, the two parts of the die being spaced by a verticallyextending channel 15 of sufl icient width and thickness to accommodatethe insulating strip 16. The insulating strip 16 consists of acontinuous length of insulating tape, preferably waterproof materialsuch as bias-cut varnished cambric. Said insulating strip 16 is fed froma suitable spool 17, and" as it is drawn through the channel 15 of thedie 14, it is preformed so that it will readily enter into the lower endof the. bore 13, the upper portion of which completes the folding-orcoiling of the strip into the form of a round tube 18 As shownin Fig. 3,said tube 18 is formed with its edges overlapping to the extent ofapproximately 100% of a complete convolution, the seam of the tube beinglongitudinal rather than spiral, avoided.

It will be understood that in the absence I of further treatment formedwithout the material for uniting the tube 18, having been aid of cementor other together its overlapping ends, by reason of the inherentresiliency of the material, would immediately spring open and againassume the shape of a strip. This" opening up of the tube is, however,prevented by applying to the tube, at the point where it emerges fromthe upper end of the die 12, a close fitting braid 19 by means of thebraiding apparatus heretofore referred to. 20 of usual construction isemployed to propel the tube through the die at a speed regulated inaccordance with the speed of application of the braid.

The braided tube, after ing machine, is conducted lating cement orvarnish which impregnates the braid, but on account of theimperviousness of the strip material, does not penetrate to the interiorof the tube. The impregnated braid is subsequently dried, either in theair drying type, or in asuitable oven if the varnish is of the bakingtype, said drying being preferably carried on as a continuous process. 1

it leaves the braid- A capstan a whereby stretching is ice into a bathof insu- The completed article fully meets there-- quirements, as itpossesses an extremely high dielectric strength. It is non-collapsibleand form-sustaining, having a smooth interior surface which does notinterfere with the insertion of the conductors. It will withstand alarge amount of abuse, and is relatively chea as compared with theItalian tubing whic it effectually displaces.

The details of description and operation are merely illustrative of asingle phase of my invention, the scope of which should be determined byreference to p the appended claims, said claims being construed asbroadly as possible consistent With the state of the art.

I claim:

1. In a non-metallic conduit, the combination of an inner liningcomprising a single strip of flexible insulating material coiledcross-Wise of the length thereof, to form a 'cross-sectionally spiral,multiwalled tube,

the edges of the strip being disposed lengthwise of the tube, and abraided cover over said tube for preventing uncoiling thereof.

2. In a non-metallic conduit, the combination of an inner liningcomprising a strip of flexible insulating material coiled crosswise ofthe length of the strip to form a double and cross sectionally spiralWalled tube, the edges of the strip being disposed lengthwise of thetube, and a braided cover over said tube for preventing uncoilingthereof.

3. The process of manufacturing non-metallic conduit of the classdescribed, which process consists in longitudinally propelling a stripof flexible insulating sheet material, coiling same cross-Wise of itslength to form same into a tube having substantially double wallsforming a spiral in cross section of the tube, and then applying afabric covering to prevent uncoiling of said tube.

HUGO I-I. WERMINE.

